Cracking hydrocarbon oils



Oct. 27, 1936. BRODERSQN 2,058,768

CRACKING HYDROCARBON OILS Filed Oct. 9, 1954 2 Sheets-Sheet 1 INVENTOR.

BY UM 6AM ATTORNEY 2 Sheets-Shed 2 Eiled Oct. 9, 1934 FI'TT llll-I I N VEN TOR.

I ATTORNEY Patented Oct. 27, 1936 Henry J. Broderson, Galveston, Tex, assignor to Standard Oil Company, a corporation of lindiana Application October 9, 1934, Serial No. 747,534

2 Claims.

This invention relates to the art of cracking hydrocarbons and pertains more particularly to an apparatus for reducing the coking difficulties adjacent the vapor outlet of an oil cracking 5 vessel.

Operating difficulties have been experienced, particularly in relatively high temperature cracking processes, due to the building up of solid coke and carbon deposits immediately adjacent the vapor outlet of the reaction chamber in which a body of hydrocarbon vapors is maintained at cracking temperature. It has been heretofore proposed to overcome this difficulty by mounting a spray ring adjacent the vapor outlet and spraying a vaporizable oil into the outlet. While this method tends to reduce the amount of coke deposits in the vapor outlet, it gives rise to coking troubles caused by the building up of solid deposits about the spray ring.

While my invention will have a more general application it is of particular advantage in cracking processes of the vapor phase type such as is described, for example, in the patent to H. R. Snow et al. 1,918,991 issued July 18, 1933 on application filed February 10, 1930. In such processes, the oil undergoing treatment is heated in a heating zone wherein it is vaporized and the vapors brought to an effective cracking temperature, at which the desired type of cracking will be accomplished and the products from the heating zone are then passed to a reaction. chamber and maintained therein above cracking temperature to eifect additional cracking. The reaction chamber is ordinarily a vertically disposed cylindrical chamber which, during the cracking operation, is substantially filled with hot dry hydrocarbon vapors with perhaps a very low level of tarry liquid in the bottom thereof.

In the cracking process of the character referred to coke formation of objectionable character has been found to form in the region of the vapor outlet.

One of the primary objects of my invention is to further reduce the coking difficulties heretofore mentioned and thereby increase the operating period of the oil cracking process and otherwise improve the operating efiiciency of the 011 cracking apparatus.

The above and other objects of the invention will be apparent from the following detailed description.

Reference is now made to the accompanying drawings in which:

55 Figure 1 is a diagrammatic elevation view illustrating a type of apparatus in which my invention may be embodied and Figure 2 shows the reaction chamber with parts broken away adjacent the vapor outlet.

Referring to the drawings the numeral 5 designates an oil cracking furnace provided with a heating coil 6 in which the oil is heated to vaporizing and cracking temperature. The oil to be heated is introduced to the coil through pipe line i provided with pump 8 and the hot cracked products after being subjected to the desired cracking are passed through the transfer line 9 to the reaction chamber ill. The products passing to the reaction chamber may be at a relatively high cracking temperature. For example, the vapors within the reaction chamber It may be at a temperature in excess of 850 F. The reaction chamber lil is provided with an inlet conduit ii, a vapor outlet l2, and an outlet conduit It for withdrawing residual products. Positioned within the vessel and surrounding the vapor outlet 52 is a spray ring M connected by means of pipe if; to suitable oil supply under pressure whereby oil may be caused to spray through nozzles It in the spray ring M in converging streams toward the vapor outlet.

In accordance with my invention I provide a protective plate ll having a central aperture in alignment with the vapor outlet but of somewhat larger diameter so as to fit snugly against the spray ring and prevent the vapors from sweeping the spray ring when passing to the vapor outlet. The inner peripheral edge of the plate ll may be curved to conform to the curvature of the spray ring and may be tapered from the inner opening to the outer edge to form a stream line flow for the outgoing vapors. The plate il may be socured to the head I 8 of the vessel I I] by weld metal or by any other suitable means.

The provision of a shield plate for the spray ring in accordance with my invention has been found to substantially eliminate troublesome coking in this region of the cracking equipment. While the exact reason for this is not definitely known, it may be explained by the fact that the vapors do not come in turbulent contact with the spray ring, through which relatively cool oil is being passed, and consequently the spray ring does not form a nucleus for the building up of carbon deposits.

While I have shown the shield plate ll as being a separate plate attached to the head of the vessel, it may be an integral portion of the vessel head in which case the head will be provided with a recess around the periphery of the vapor outlet and the spray ring secured within the recess. As a further alternative the spray ring may be in the form of an annular channel formed within the head of the vessel or in the vapor outlet pipe with nozzle openings connecting the annular channel with the interior of the Vapor outlet.

Having described the preferred embodiment of the invention, it will be understood that various other modifications may be employed without departing from the spirit. of my invention.

What I claim is:

1. An oil-cracking vessel comprising a metal shell forming an enclosed chamber and having a passage leading from the interior of that chamber for removal of vapors therefrom, the inner end of such passage being of enlarged diameter to form an annular recess, a tubular spray ring mounted within said recess having nozzle openings positioned to direct converging streams of oil toward said. outlet passage, and a pipe adapted to connect said spray ring with a charge of oil under pressure.

2. In an oil-cracking vessel having a metallic shell forming an enclosed chamber and a vapor conduit leading from the interior for the removal of vapors therefrom, a tubular spray ring having inwardly extending nozzle openings for projecting sprays of oil towards said conduit mounted within the chamber and abutting the inner end of said conduit, means for supplying said tubular spray ring with oil, an annular plate secured to the inner wall of said shell and extending to said spray ring to form with said spray ring a smooth inner face within the chamber.

HENRY J. BRODERSON. 

